Oncolytic virus replicating selectively in tumor cells

ABSTRACT

By using a virus having a gene sequence comprising a telomerase promoter and an E1 gene (preferably a sequence comprising E1A gene, IRES sequence and E1B gene) or by using an anticancer agent comprising the virus, the virus replicates in cancer cells to thereby produce an efficient anticancer effect.

This application is a continuation-in-part application of U.S. application Ser. No. 10/520,901, which is the U.S. National Phase under 35 U.S.C. §371 of International Patent Application No. PCT/JP2003/008573, filed Jul. 7, 2003, and claims the benefit of priority under 35 U.S.C. §119(a)-(d) of JP application 2002-198941 filed on Jul. 8, 2002. Each of the aforementioned applications is hereby incorporated by reference in its entirety.

REFERENCE TO SEQUENCE LISTING

Pursuant to 37 C.F.R. 1.821(c), a sequence listing is submitted herewith as an ASCII compliant text file named “Sequence Listing.txt” that was created on Jul. 19, 2010 and has a size of 106,772 bytes. The content of the aforementioned file named “Sequence listing.txt” is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a virus showing antitumor effect by replicating in tumor cells; a polynucleotide contained in the virus; an anticancer agent comprising the virus; and a method of treating cancers using the virus.

BACKGROUND ART

At present, gene therapy is performed as one method for treating cancers. However, since a gene is introduced into diseased tissue or the like with a non-replication competent virus vector in gene therapy, the gene can be applied to only those regions around target cells taking into consideration the safety of the human body. Also, in the gene therapy currently practiced, satisfactory therapeutic effect cannot be achieved because of low efficiency in gene transfer.

It is known that telomerase activity is often enhanced in malignantly transformed cells or immortalized cell strains, whereas telomerase activity is hardly detected in normal somatic cells excluding such as germ line cells, blood lineage cells and epithelial stem cells.

Under circumstances, it is a major object of the present invention to let a virus grow in tumor cells by utilizing the telomerase activated therein to thereby bring death to the tumor cells efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic drawing of the structure of a oncolytic virus replicating selectively in tumor cells. A replication cassette consisting of hTERT promoter, E1A gene, IRES sequence and E1B gene is inserted in the E1 gene region which non-replication competent virus vectors lack.

FIG. 2 shows comparison of telomerase activities in human cancer cells and normal cells.

FIG. 3 shows the expression of E1A and E1B mRNAs and proteins after TRAD infection in human cancer cells and normal cells.

FIG. 4 shows the intracellular replication of the virus after TRAD infection in human cancer cells and normal cells.

FIG. 5 presents photographs showing, by staining with Coomassie brilliant blue, the cytotoxicity caused by TRAD in human cancer cells and normal cells.

FIG. 6 presents microscopic photographs showing the cytotoxicity caused by TRAD in human cancer cells and normal cells.

FIG. 7 presents graphs showing by means of XTT assay the cytotoxicity caused by TRAD in human cancer cells and normal cells.

FIG. 8 is a graph showing the antitumor effect produced by intratumoral, local administration of a non-replication competent, p53 gene-expressing adenovirus vector in an experiment using nude mice and human lung cancer cell H358.

FIG. 9 is a graph showing the antitumor effect produced by intratumoral, local administration of TRAD in an experiment using nude mice and human large bowel cancer cell SW620.

FIG. 10 presents photographs showing the results of CT scan on the human cancer patients or the results of staining of tumor lesion.

DISCLOSURE OF THE INVENTION

The present inventors have found for the first time that, by infecting cancer cells with a virus having a telomerase promoter and replication ability, it is possible to let the virus replicate in the cancer cells and bring death to them. Thus, the present invention has been achieved.

The present invention relates to the following items 1 to 11.

-   1. A polynucleotide cassette comprising an hTERT promoter operably     linked with an E1A gene, an IRES sequence and an E1B gene in this     order. -   2. The polynucleotide cassette according to item 1 above, wherein     the E1A gene comprises a nucleotide sequence selected from the group     consisting of: -   a) the nucleotide sequence of SEQ ID NO: 1; and -   b) a nucleotide sequence having at least 90% identity to the     nucleotide sequence of SEQ ID NO: 1, wherein the nucleotide sequence     encodes a polypeptide having an E1A activity. -   3. The polynucleotide cassette according to item 1 above, wherein     the E1B gene comprises a nucleotide sequence selected from the group     consisting of: -   a) the nucleotide sequence of SEQ ID NO: 2 or 9; and -   b) a nucleotide sequence having at least 90% identity to the     nucleotide sequence of SEQ ID NO: 2 or 9, wherein the nucleotide     sequence encodes a polypeptide having an E1B activity. -   4. The polynucleotide cassette according to item 1 above, wherein     the IRES sequence comprises a nucleotide sequence selected from the     group consisting of: -   a) the nucleotide sequence of SEQ ID NO: 3 or 10; and -   b) a nucleotide sequence having at least 90% identity to the     nucleotide sequence of SEQ ID NO: 3 or 10, wherein the nucleotide     sequence has an IRES activity. -   5. The polynucleotide cassette according to item 1 above, wherein     the hTERT promoter comprises a nucleotide sequence selected from the     group consisting of: -   a) the nucleotide sequence of SEQ ID NO: 4; and -   b) a nucleotide sequence having at least 90% identity to the     nucleotide sequence of SEQ ID NO: 4, wherein the nucleotide sequence     has an hTERT promoter activity. -   6. The polynucleotide cassette according to item 1 above, comprising     a nucleotide sequence selected from the group consisting of: -   a) the nucleotide sequence of SEQ ID NO: 11 or 12; and -   b) a nucleotide sequence having at least 90% identity to the     nucleotide sequence of SEQ ID NO:11 or 12, wherein the nucleotide     sequence encodes a polypeptide having an activity to enable an     adenovirus to replicate selectively in tumor cells. -   7. A recombinant adenovirus comprising the polynucleotide cassette     according to any one of items 1 to 6 above. -   8. The recombinant adenovirus according to item 7 above, comprising     a nucleotide sequence selected from the group consisting of: -   a) the nucleotide sequence of SEQ ID NO: 13; and -   b) a nucleotide sequence having at least 90% identity to the     nucleotide sequence of SEQ ID NO:13, wherein the nucleotide sequence     encodes a polypeptide having an activity to enable an adenovirus to     replicate selectively in tumor cells. -   9. The recombinant adenovirus according to item 7 above, comprising     a nucleotide sequence selected from the group consisting of: -   a) the nucleotide sequence of SEQ ID NO: 14; and -   b) a nucleotide sequence having at least 90% identity to the     nucleotide sequence of SEQ ID NO:14, wherein the nucleotide sequence     encodes a recombinant adenovirus having an activity to replicate     selectively in tumor cells. -   10. A method of treating a cancer comprising administering an     effective amount of the recombinant adenovirus according to any one     of items 7 to 9 above to a patient in need thereof. -   11. The method according to item 10, wherein the cancer is at least     one cancer selected from the group consisting of stomach cancer,     large bowel cancer, lung cancer, liver cancer, prostate cancer,     pancreas cancer, esophagus cancer, bladder cancer, gallbladder/bile     duct cancer, breast cancer, uterine cancer, thyroid cancer and     ovarian cancer, osteosarcoma and brain tumor.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is characterized by bringing death to cancer cells by infecting cancer cells with a virus having a telomerase promoter and replication ability and letting the virus grow in the cancer cells, based on the finding that a wide variety of cancer cells have telomerase activity.

The virus used in the present invention is not particularly limited. From the viewpoint of safety, adenovirus is preferable. Among adenovirus species, type 5 adenovirus is particularly preferable from the viewpoint of, for example, easiness in use.

E1 gene contained in viral polynucleotide refers to one of early genes of viruses. Viruses have early (E) genes and late (L) genes involved in their DNA replication. E1 gene encodes a protein involved in the regulation of transcription of viral genome.

The E1 gene used in the present invention may be derived from any virus. Preferably, an adenovirus-derived E1 gene is used.

It is known that E1 gene is composed of E1A, E1B and other elements. E1A protein encoded by E1A gene activates the transcription of a group of genes (E1B, E2, E4, etc.) necessary for the production of infectious virus.

In a preferred embodiment of the invention, the E1A gene comprises the nucleotide sequence of SEQ ID NO: 1 or a variant thereof. The variant of E1A comprises the nucleotide sequence having at least 90%, preferably at least 95%, more preferably at least 96%, and even more preferably at least 97%, 98%, or 99% identity to that of SEQ ID NO: 1, wherein the nucleotide sequence encodes a polypeptide having an E1A activity.

Identity of any two nucleotide sequences can be determined by those skilled in the art based, for example, on a BLAST 2.0 computer alignment. BLAST 2.0 searching is known in the art and is publicly available, for example, at ncbi.nlm.nih.gov/BLAST/.

E1B protein encoded by E1 B gene assists the accumulation of late gene (L gene) mRNA in the cytoplasm of the infected host cell to thereby inhibit the protein synthesis in the host cell. Thus, E1B protein promotes viral replication.

In a preferred embodiment of the invention, the E1B gene comprises the nucleotide sequence of SEQ ID NO: 2 or 9. In another preferred embodiment of the invention, the E1B gene comprises a variant of the nucleotide sequence of SEQ ID NO: 2 or 9. The variant of E1B comprises the nucleotide sequence having at least 90%, preferably at least 95%, more preferably at least 96%, and even more preferably at least 97%, 98%, or 99% identity to that of SEQ ID NO: 2 or 9, wherein the nucleotide sequence encodes a polypeptide having an E1B activity. The identity between the nucleotide sequences of SEQ ID NO: 2 and SEQ ID NO: 9 is about 99%.

In the present invention, a known E1 gene may be used as it is. Preferably, an E1 gene having an E1A gene, an IRES sequence and an E1B gene in this order (i.e., an E1 gene in which an IRES sequence is inserted between its E1A gene and E1B gene) is used. With the use of such an E1 gene, the replication ability of the virus of the invention will be high when a host cell has been infected with the virus.

As long as the effect of the invention can be achieved, at least one nucleotide may be inserted into at least one site selected from the group consisting of (a) between IRES sequence and E1A gene, (b) between IRES sequence and E1B gene, (c) upstream of E1A gene, and (d) downstream of E1B gene. As long as the effect of the invention can be achieved, at least one, preferably several nucleotides may be substituted, deleted, inserted or added in the E1A gene, IRES sequence, E1B gene or E1 gene.

“IRES sequence” is a protein synthesis initiation signal specific to picornavirus. It is believed that this sequence serves as a ribosome-binding site because it contains a complementary sequence to the 3′ terminal sequence of 18S ribosomal RNA. It is known that picornavirus-derived mRNA is translated via this sequence.

Translation efficiency from IRES sequence is high. Even from the middle of mRNA, protein synthesis is performed in a cap structure non-dependent manner. Therefore, in the virus of the present invention, both E1A gene and E1B gene located downstream of the IRES sequence are translated independently by a promoter from human telomerase.

In a preferred embodiment of the invention, the IRES sequence comprises the nucleotide sequence of SEQ ID NO: 3 or 10. In another preferred embodiment of the invention, the IRES sequence comprises a variant of the nucleotide sequence of SEQ ID NO: 3 or 10. The variant of the IRES sequence comprises the nucleotide sequence having at least 90%, preferably at least 95%, more preferably at least 96%, and even more preferably at least 97%, 98%, or 99% identity to that of SEQ ID NO: 3 or 10, wherein the nucleotide sequence has an IRES activity. The identity between the nucleotide sequences of SEQ ID NO:3 and SEQ ID NO: 10 is about 97%.

In the present invention, it is preferable that E1 gene has a promoter from human telomerase upstream thereof, because such a promoter is capable of promoting the replication of the virus of the invention in cancer cells having telomerase activity. The promoter from human telomerase is not particularly limited as long as the promoter is derived from human. Among all, hTERT promoter is preferable.

hTERT is a gene encoding human telomerase reverse transcriptase. A number of transcription factor-binding sequences are confirmed in a 1.4 kbp region upstream of the 5′ end of this gene. This region is believed to be hTERT promoter. In particular, a 181 bp sequence located upstream of the translation initiation site is a core region important for the expression of the downstream gene.

In the present invention, any sequence comprising this core region may be used as a promoter from human telomerase. Preferably, an upstream sequence of approximately 378 bp containing the core region completely is used. It has been confirmed that this sequence of approximately 378 bp is equivalent to the 181 bp core region alone in gene expression efficiency.

In a preferred embodiment of the invention, the hTERT promoter comprises the nucleotide sequence of SEQ ID NO: 4 or a variant thereof. The variant of the hTERT promoter comprises the nucleotide sequence having at least 90%, preferably at least 95%, more preferably at least 96%, and even more preferably at least 97%, 98%, or 99% identity to that of SEQ ID NO: 4, wherein the nucleotide sequence has an hTERT promoter activity.

A gene having the telomerase promoter of the invention and the E1 gene of the invention (a gene comprising E1A gene, IRES gene and E1B gene) may be obtained by conventional genetic engineering techniques.

As the E1 gene, an E1 gene from a known virus having that gene may be used. Preferably, an E1 gene derived from adenovirus is used.

Alternatively, E1A gene and E1B gene may be amplified from E1 gene-expressing cells (preferably, E1 gene-expressing 293 cells or the like) by RT-PCR and/or DNA-PCR using primers such as E1A-S, E1A-AS, E1B-S and E1B-AS. If necessary, their sequences are confirmed using a conventional method such as TA cloning. Then, E1A and E1B DNA fragments may be cut out using a known restriction enzyme such as EcoRI.

E1A and E1B may be inserted into a known vector such as pIRES by conventional genetic engineering techniques to thereby prepare E1A-IRES-E1B sequence within the vector. Subsequently, hTERT promoter sequence which was cut out with restriction enzymes such as MluI and BglII may be inserted into the XhoI site or the like located upstream of E1A. As a result, a polynucleotide cassette comprising an hTERT promoter operably linked with an E1A gene, an IRES sequence and an E1B gene in this order can be obtained.

In a preferred embodiment of the invention, hTERT promoter and E1A gene, E1A and IRES sequence, IRES sequence and E1B gene may be linked by spacer sequences. It is known that, there are many cases in which the shorter the spacer sequences are, the higher the translation efficiency of genes is. Meanwhile, the longer the spacer sequences are, the more the number of restriction enzyme sites that can be utilized is, and therefore, a vector can be easily constructed. In view of these matters, length of the spacer sequence is, preferably 0 to about 100 base pair, more preferably 0 to about 50 base pair, even more preferably 0 to about 35 base pair. Example sequence of spacer is a nucleotide sequence shown in SEQ ID NO: 27, 28 or 29. It is difficult for one of skill in the art that hTERT promoter and E1A gene, E1A and IRES sequence, IRES sequence and E1B gene is linked by such short spacer sequences and the recombinant virus of the invention is constructed.

In another preferred embodiment of the invention, the polynucleotide cassette comprises the nucleotide sequence of SEQ ID NO: 11 or 12 or a variant thereof. The variant of the polynucleotide cassette comprises the nucleotide sequence having at least 90%, preferably at least 95%, more preferably at least 96%, and even more preferably at least 97%, 98%, or 99% identity to that of SEQ ID NO: 11 or 12, wherein the nucleotide sequence encodes a polypeptide having an activity to enable an adenovirus to replicate selectively in tumor cells. The activity can be determined by infecting the adenovirus to tumor cells and measuring viral titer of the adenovirus (see e.g., Example 4 of the present specification).

If necessary, cytomegalovirus (CMV) promoter contained in a known vector such as pShuttle may be removed with restriction enzymes such as MfeI and NheI; then, a sequence cut out from phTERT-E1A-IRES-E1B with restriction enzymes NheI and NotI may be inserted into the site (resultant vector is designated “pSh-hAIB”).

From the resultant pSh-hAIB, a sequence comprising necessary portions (including hTERT promoter, E1A gene, IRES sequence and E1B gene) may be cut out with restriction enzymes such as I-CeuI and Pl-SceI, and then inserted into a viral DNA such as Adeno-X Viral DNA using a commercial kit such as Adeno-X Expression System (Clontech) (the resultant DNA is designated “AdenoX-hAIB”).

The above-described sequence comprising hTERT promoter, E1A gene, IRES sequence and E1B gene may be inserted into any site of a viral gene as long as the effect of the present invention can be achieved. For example, in adenovirus for gene therapy from which E1 gene has been deleted, the above-described sequence is preferably inserted into the deleted site.

It is possible to linearize AdenoX-hAIB with a known restriction enzyme such as PacI and then transfect into cultured cells such as 293 cells, to thereby prepare a infectious recombinant adenovirus (the resultant virus is sometimes called the “virus of the present invention” or “TRAD”). The method of transfection is not particularly limited. From the viewpoint of efficiency, such methods as the calcium phosphate method or electroporation may be preferable.

In a preferred embodiment, the nucleotide sequence of the recombinant adenovirus comprises the above-described polynucleotide cassette comprising the nucleotide sequence of SEQ ID NO: 11 or 12 or a variant thereof. In another preferred embodiment, the nucleotide sequence of the recombinant adenovirus comprises that of SEQ ID NO: 13 or a variant thereof. The variant comprises the nucleotide sequence having at least 90%, preferably at least 95%, more preferably at least 96%, and even more preferably at least 97%, 98%, or 99% identity to that of SEQ ID NO: 13, wherein the nucleotide sequence encodes a polypeptide having an activity to enable an adenovirus to replicate selectively in tumor cells. The activity can be determined by infecting the adenovirus to tumor cells and measuring viral titer of the adenovirus (see e.g., Example 4 of the present specification). The nucleotide sequence of SEQ ID NO: 13 is the nucleotide sequence from the first position of the genome of the recombinant adenovirus to the position just before the first position of the E3 region thereof.

In another preferred embodiment, the nucleotide sequence of the recombinant adenovirus can be that of SEQ ID NO: 14 or a variant thereof. The variant can be the nucleotide sequence having at least 90%, preferably at least 95%, more preferably at least 96%, and even more preferably at least 97%, 98%, or 99% identity to that of SEQ ID NO: 14, wherein the nucleotide sequence encodes a recombinant adenovirus having an activity to replicate selectively in tumor cells. The activity can be determined by infecting the adenovirus to tumor cells and measuring viral titer of the adenovirus (see e.g., Example 4 of the present specification).

The thus obtained virus of the present invention can be replicated by conventional methods for viral replication, e.g. infecting host cells such as 293 cells with the virus.

The virus of the present invention may be used as an anticancer agent. This anticancer agent may be used not only for treating cancers but also for preventing postoperative relapse of cancers, preventing cancer metastasis and/or for prophylaxis of cancers.

The kinds of cancers to which the anticancer agent of the invention is applied are not particularly limited. The anticancer agent is applicable to any kind of cancer. For example, the anticancer agent is effective for cancers in the stomach, large bowel, lung, liver, prostate, pancreas, esophagus, bladder, gallbladder/bile duct, breast, uterus, thyroid, ovary, etc. as well as brain tumor and osteosarcoma. Among all, the anticancer agent is especially effective for solid tumor.

The anticancer agent of the invention may be applied to diseased sites as it is. Alternatively, the anticancer agent may be introduced into humans (target cells or organs) by any known method, e.g. intravenous, intramuscular, intraperitoneal or subcutaneous injection; inhalation through the nasal cavity, oral cavity or lung; oral administration; administration in the form of suppository; and administration in the form of external medicine.

The virus of the invention may be treated, for example, by the lyophilization method to enable easy handling and then used alone, or prepared into pharmaceutical compositions by mixing with known pharmaceutically acceptable carriers such as excipients, fillers, binders, lubricants; or known additives (including such as buffers, isotonic agents, chelating agents, coloring agents, preservatives, flagrances, flavoring agents, and sweetening agents).

The anticancer agent of the present invention may be administered orally or parenterally depending on the form of the agent, e.g. oral administration agents such as tablets, capsules, powders, granules, pills, liquids, syrups, etc. and parenteral administration agents such as injections, external medicines, suppositories, eye drops, etc. Preferably, local injection into muscle or abdominal cavity, or intravenous injection may be enumerated.

Dose levels are selected appropriately depending on the kind of active ingredient, the administration route, the target of administration, and the age, body weight, sex, symptoms and other conditions of the patient. Usually, dose levels may be selected so that the virus of the invention (the active ingredient) is administered at a daily dose of about 10⁶-10¹¹ PFU, preferably about 10⁹-10¹¹ PFU. This amount may be administered once a day, or may be divided into several portions and administered at several times a day.

When the virus of the invention is administered, it is also possible to use a known immunosuppressant or the like to suppress the immunity of the living body to thereby make the viral infection easy.

Further, the virus of the invention may be used jointly with at least one anticancer agent selected from the group consisting of non-replication competent viruses (such as virus comprising p53 gene) used in conventional gene therapy, known anticancer agents and radiation.

The virus of the invention infected to the living body (cancer cells or cancer tissues) is capable of replicating in the cancer cells and bringing death to those cells. By thus bringing death to cancer cells, the virus of the invention can treat cancers, inhibit the growth of tumor cells, and prevent metastasis of cancer cells.

It is believed that there is an extremely low possibility that the anticancer agent of the invention will produce side effects for the reasons described below. Thus, the anticancer agent of the invention can be said a very safe preparation.

-   (1) There is little telomerase activity in normal somatic cells, and     yet adenovirus itself is hard to be infected to suspending cells     such as hematopoietic cells. Therefore, when adenovirus is used in     the present invention, still higher selectivity for tumor kinds is     obtained. -   (2) Since the virus of the invention has replication ability, it is     possible to use this virus at a lower concentration than that of     conventional non-replication competent virus used in conventional     gene therapy. -   (3) Even when the virus of the invention has been administered in     excess, antiviral action works through ordinary immune reaction in     the living body.

EXAMPLES

Hereinbelow, examples will be provided in order to illustrate the present invention in more detail. Needless to say, the present invention is not limited to these examples.

Example 1

<Preparation of TRAD>

An E1A gene of 899 bp was amplified from RNA extracted from 293 cells by RT-PCR using specific primers (E1A-S: SEQ ID NO: 5; E1A-AS: SEQ ID NO: 6). An E1B gene of 1823 bp was amplified from DNA extracted from 293 cells by DNA-PCR using primers (E1B-S: SEQ ID NO: 7; E1B-AS: SEQ ID NO: 8).

These PCR products were subjected to TA cloning (TA Cloning Kit Dual Promoter; Invitrogen) to thereby confirm their sequences. Then, DNA fragments of 899 bp (E1A) and 1823 bp (E1B) were cut out, respectively, with restriction enzyme EcoRI.

E1A and E1B were inserted into the MluI site and the SalI site of pIRES vector (Clontech), respectively, in the normal orientation (E1A-IRES-E1B).

A 455 bp hTERT promoter sequence which had been cut out with restriction enzymes MluI and BglII was inserted into the XhoI site located upstream of the E1A of E1A-IRES-E1B (phTERT-E1A-IRES-E1B).

The cytomegalovisus (CMV) promoter contained in pShuttle vector was removed by treatment with restriction enzymes MfeI and NheI. Then, a 3828 bp sequence cut out from phTERT-E1A-IRES-E1B using restriction enzymes NheI and NotI was inserted into that site (pSh-hAIB).

A 4381 bp sequence was cut out from pSh-hAIB using restriction enzymes I-CeuI and Pl-SceI, and inserted into the Adeno-X Viral DNA of Adeno-X Expression System (Clontech) (AdenoX-hAIB). This AdenoX-hAIB was treated with restriction enzyme PacI for linearization and then transfected into 293 cells by the phosphate calcium method. Thus, a infectious recombinant adenovirus (TRAD) was prepared. A schematic drawing of TRAD is shown in FIG. 1.

Example 2

<Comparison of Telomerase Activities in Human Cancer Cells and Normal Cells>

RNA was extracted from the following 10 kinds of cells using RNAzol (Cinna/Biotecx): human lung cancer cells (A549, H226Br and H1299); human large bowel cancer cells (SW620, DLD-1 and LoVo); human embryonic kidney cell 293; human umbilical vascular endothelial cell HUVEC immortalized by the introduction of SV40 gene; and human normal fibroblast cells (WI38 and NHLF). The resultant RNA was subjected to real time quantitative reverse transcription (RT)-PCR using Light Cycler DNA TeloTAGGG Kit (Roche Molecular Biochemicals), followed by comparison of expression levels of hTERT gene in respective cells. The results are shown in FIG. 2.

When expression levels were compared taking the level in A549 cells (which showed the highest expression) as 1.0, hTERT gene expression from 0.18 to 1.00 was observed in cancer cells (such as A549, H226Br, H1299, SW620, DLD-1, Lovo) and 293 cells, whereas no expression was detected in immortalized cell HuVEC and normal cells (such as WI38, NHLF).

Example 3

<Expression of E1A and E1B mRNAs and Proteins after TRAD Infection in Human Cancer Cells and Normal Cells>

Human large bowel cancer cell SW620 and human normal fibroblast cell WI38 were cultured in vitro. Then, each cell was infected with TRAD at concentrations of MOI (multiplicity of infection) 0.1 and 1, followed by recovery of RNA after 36 hours. As a positive control, 293 cells were used.

The recovered RNA was reverse-transcribed using GeneAmp RNA PCR Core Kit. The resultant DNA was amplified 30 cycles in GeneAmp PCR System 9700 Thermal Cycler (PE Applied Biosystems) using primers for E1A gene and E1B gene. The PCR products were electrophoresed on 1.2% agarose gel and stained with ethidium bromide to thereby visualize bands (upper two panels in FIG. 3A). The intensities of the bands were measured with an image analyzer, quantitatively determined using GAPDH as an internal control and then shown in graphs (the bottom panel in FIG. 3A).

Human large bowel cancer cell SW620 and human normal fibroblast cell WI38 were cultured in vitro. Then, each cell was infected with TRAD at concentrations of MOI 0.1 and 1. After 48 hours, adherent cells were recovered and reacted in a lysis solution for 30 minutes, followed by centrifugation. The protein concentration in the resultant supernatant was measured. Briefly, the supernatant was electrophoresed on 12% polyacrylamide gel and transferred onto a membrane. Then, Western blot analysis was performed with anti-adenovirus 5 E1A antibody (PharMingen International). The results are shown in FIG. 3B.

While strong expression of E1A gene (502 bp) and E1B gene (543 bp) was clearly observed as a result of TRAD infection in cancer cell SW620, only weak expression of these genes was observed in normal cell WI38 (FIG. 3A). In the positive control 293 cells, medium expression of these genes was observed.

The results of Western blot analysis revealed that expression of E1A protein increased in SW620 as the concentration of TRAD increased from MOI 0.1 to 1 (FIG. 3B). On the other hand, expression of E1A protein was detected little in WI38 even when TRAD was used at MOI 1.

Example 4

<Examination of Intracellular Viral Replication after TRAD Infection in Human Cancer Cells and Normal Cells>

Human cancer cells (SW620 and H1299) and human normal cells (WI38 and NHLF) were infected with TRAD at MOI 1 for 2 hours at 37° C. Then, the TRAD-containing culture broth was discarded. After cells were washed with a fresh culture broth once, a fresh culture broth was added further. Immediately thereafter (i.e., on day 0), cells were recovered with a scraper and subjected to repetition of freezing and thawing. Then, they were suspended in 1 ml of a culture broth. Further, virus was recovered on day 1, 2, 3, 5 and 7 in the same manner, followed by measurement of viral titer. The results are shown in FIG. 4.

In normal cells WI38 and NHLF, TRAD increased from 10² PFU on day 1 to about 10⁵ PFU on day 3 showing 100- to 1000-fold growth. On the other hand, in cancer cells SW620 and H1299, TRAD increased to 10⁷-10⁸ PFU showing 10⁵- to 10⁶-fold growth. Thus, viral growth specific to cancer cells was confirmed.

Example 5

<Cytotoxic Activity of TRAD in Human Cancer Cells and Normal Cells>

Five kinds of human cancer cells (SW620, H1299, A549, DLD-1 and H226Br) were plated on 24-well plates at 6-8×10⁴ cells/well, and two kinds of human normal cells (WI38 and NHLF) were plated on 24-well plates at 2-4×10⁴ cells/well. After 24 hours, they were infected with TRAD at MOI 0.01, 0.1, 1, 2 and 5. Ninety-six hours after the infection, morphological changes in SW620, DLD-1 and NHLF cells were observed under microscopy. Further, culture broth was discarded from all of the cells. Then, viable cells were stained with Coomassie brilliant blue, and macroscopic images were taken into with a scanner.

SW620 and H1299 were plated at 10⁴ cells/well and NHLF was plated at 5×10³ cells/well, respectively, on 96-well plates. Cells were infected with TRAD at MOI 0 (non-infected cells), 0.01, 0.1 and 1. Then, the numbers of viable cells were measured by XTT assay on day 1, 2, 3, 5 and 7. The viable cell count was determined for each four wells. Taking the count in the non-infected cells as 1.0, counts in other cells were represented in graphs in means+/−SDs. Respective results are shown in FIGS. 5, 6 and 7.

In cancer cells SW620, H1299, A549, DLD-1 and H226Br, cell counts decrease and areas stained with blue reduce in a TRAD concentration-dependant manner. On the other hand, in normal cells WI38 and NHLF, no remarkable decrease in the number of viable cells stained with blue was recognized (FIG. 5). In the microscopic observation, SW620 and DLD-1 cells were peeled off from the plate bottom, became round-shaped and showed decrease in cell density; on the other hand, NHLF cells showed little morphological change and no decrease in cell count (FIG. 6).

In SW620 and H1299 cells, almost 100% cell death was observed by day 3 as a result of TRAD infection at MOI 1. More than 80% decrease in cell count was recognized even at MOI 0.1. On the other hand, NHLF showed almost no decrease in cell count even on day 3. Although NHLF showed about 60% decrease in cell count on day 7 when TRAD was used at MOI 1, it indicated no viral influence at MOI 0.01 (FIG. 7).

Example 6

<Examination of the Antitumor Activity of TRAD in Animal Models>

Human lung cancer cell H358 was transplanted subcutaneously into the back of 5-6 week-old nude mice at 5×10⁶ cells/mouse. When the tumor became approximately 5-6 min in diameter, a non-replication competent adenovirus vector (Ad-p53) was injected intratumorally and locally for consecutive two days at 1×10⁸ PFU, 3×10⁸ PFU and 1×10⁹ PFU per day. Then, two axes of each tumor crossing at right angles were measured at regular intervals. The estimated tumor weight was calculated by the following formula: (major axis)×(minor axis)²/2. As a control, a non-replication competent adenovirus vector dl312 containing no inserted gene was used.

Human large bowel cancer cell SW620 was transplanted subcutaneously into the back of 5-6 week-old nude mice at 5×10⁶ cells/mouse. When the tumor became approximately 5-6 mm in diameter, 2×10⁷ PFU of dl312/day and 4×10³ PFU of TRAD/day were injected intratumorally and locally for consecutive three days. The axes of each tumor were measured in the same manner as described above, followed by calculation of the estimated tumor weight. The results are shown in FIGS. 8 and 9 (the term “Mock” appearing in these Figures represents control to which PBS (phosphate buffered saline) was administered).

Administration of Ad-p53 at 3×10⁸ PFU and 1×10⁹ PFU inhibited the growth of H358 tumor significantly (p<0.05). However, administration of Ad-p53 at 1×10⁸ PFU revealed no significant growth inhibition (FIG. 8). Administration of dl312 (control) indicated no influence upon tumor growth.

Intratumoral administration of TRAD at 4×10³ PFU, which is extremely lower than the concentration of Ad-p53 that showed antitumor effect, inhibited the growth of SW620 tumor significantly (p<0.05). Administration of dl312 (control) indicated no influence upon tumor growth.

From what have been described above, it is understood that the virus of the present invention grows efficiently in cancer cells and brings death to them. Further, since the virus of the invention has the ability to grow, it is capable of manifesting potent anti-cancer effect even at a low concentration. Thus, it is also possible to reduce side effect by administering the virus at a low concentration.

Example 7

<Full Sequencing of TRAD Genome>

In the present example, a full sequencing of TRAD genome was performed by constructing a shotgun library and sequencing the clones to provide 4-fold sequencing data that covers at least one of the two DNA strands.

I. Method

-   (1) Test Samples

In this Example, 1.0×10¹² particles/ml of TRAD was used as a test sample. The test samples had been stored −80° C.

-   (2) Shotgun Library Construction and DNA Sequencing -   (2-1) Shotgun Library Construction

Adenoviral DNA was prepared from the test article using a Qiagen viral DNA extraction method. The test article DNA was fragmented and cloned into the Sma I site of the pUC 19 vector to create a shotgun library.

-   (2-2) DNA Quality Control

Plasmid DNA was prepared from the shotgun library subclones and the presence of inserts was verified by agarose gel electrophoresis of a subset of subclones. The DNA concentrations for a subset of subclones were determined by OD260 reading using a spectrophotometer.

-   (2-3) Sequencing and Assembly

A total of 384 shotgun library clones were sequenced with pUC forward and reverse vector primers for a total of 768 reactions using the BigDye (registered trademark) Terminator vl. 1 Cycle Sequencing Kit (Applied Biosystems). The data were screened for host and vector DNA sequences and assembled to derive a consensus sequence using the phred/phrap/consed suite of programs on a Linux platform. Sequencing of gaps and terminal repeats was performed by direct sequencing of the adenoviral DNA and sequencing of shotgun subclones derived from the construct. Additional sequencing primers used for gap closure and sequence coverage are given in the following table. An additional 112 finishing reactions were performed. Quality values were determined for each base of the contig. The majority of bases for the consensus sequence had a quality score of 90. The quality score was determined using Phred scaled from 0 to 90 with 90 indicating the highest quality. A score value above 90 indicates a manual editing of that base.

Additional Sequencing Primers Primer Name Sequence AP01 GAGAGGTCGAATCGGCCTAG SEQ ID NO: 15 AP02 CTTCGCAGGGCCAGCTGAAC SEQ ID NO: 16 AP05 TAACGAGCCTGGGCAACCT SEQ ID NO: 17 AP06 GTCGGTCAAGCCTTGCCTTG SEQ ID NO: 18 AP07 CCTTATAAGCATAAGACGGAC SEQ ID NO: 19 AP08 CAGCTCAATCAGTCACAGTG SEQ ID NO: 20 AP09 GTCAAGAAGACAGGGCCAGG SEQ ID NO: 21 AP10 GGCTGTGGAATGTATCGAGG SEQ ID NO: 22 AP11 TAATGTTGTCTCTACGCCTG SEQ ID NO: 23 AP12 AACCGCACGCGAACCTACG SEQ ID NO: 24 AP13 GGCCGAACACTCGTGCTGG SEQ ID NO: 25 AP14 TCTGCGAAACCGCCTCCTC SEQ ID NO: 26 II. Result

The assembly resulted in a contig, consisting of 732 reads with a contig length of 37, 289 bp (SEQ ID NO: 14). This result demonstrated that TRAD comprises a nucleotide sequence of SEQ ID NO: 14.

TRAD comprising the nucleotide sequence of SEQ ID NO: 14 was used in the following Clinical Trial (Example 8).

Example 8

<Clinical Trial of TRAD>

Presented herein are results of a clinical trial using TRAD, an adenovirus containing: hTERT promoter+E1A-IRES-E1B construct. The methods utilized in the clinical trials also fall within the scope of the presently claimed methods for treating a cancer. The results of the clinical trails described herein further illustrate the ability of the claimed polynucleotide and vector constructs to replicate in cancer cells as well as to kill the cancer cells. This clinical trial was done under the inventor's supervision.

A phase I study was designed to determine the feasibility and to characterize the pharmacokinetics of TRAD in patients with advanced solid tumors.

I. Method

A phase I dose-escalation trial was conducted in patients with histologically-confirmed solid tumors (n=16) total; TRAD was injected directly into an index tumor <25 cm² and >1 cm² at single, ascending doses of 1×10¹⁰, 1×10¹¹, and 1×10¹² viral particles/tumor. All patients had failed standard chemo and radiotherapy.

II. Result

Sixteen patients (3 patients in cohort 1 and cohort 2, 10 patients in cohort 3) were treated. The primary tumor types were head and neck (n=2), breast (n=1), soft tissue (n=1), and others (n=5). Mild to moderate fatigue (56%), chills (38%), pyrexia (38%), injection site pain (31%) were the most commonly reported adverse events. Dose-limiting toxicity and unexpected severe adverse events were not observed. Nine out of 11 patients evaluated for response had stable disease at the day 28 assessment, and 9 patients showed 6.7% to 45.5% tumor size reduction. These results are summarized in the following tables 1 and 2.

TABLE 1 First Occurrence of All Adverse Events Reported by At Least 20% of Patients 1 × 10¹⁰ VP 1 × 10¹¹ VP 1 × 10¹² VP Total System Organ Class (N = 3) (N = 3) (N = 10) (N = 16) Preferred Term N (%) N (%) N (%) N (%) General Disorders and Administration Site Conditions Chills 0 0 6 6  (0%)  (0%) (60%) (38%) Fatigue 1 2 6 9 (33%) (67%) (60%) (56%) Injection Site 1 1 2 4 Erythema (33%) (33%) (20%) (25%) Injection Site Pain 1 2 2 5 (33%) (67%) (20%) (31%) Pain 0 2 2 4  (0%) (67%) (20%) (25%) Pyrexia 0 0 6 6  (0%)  (0%) (60%) (38%) Nervous System Disorders Headache 1 2 1 4 (33%) (67%) (10%) (25%)

TABLE 2 Tumor size assessment - treated target lesion No. Dose Primary Injection Site Tumor Size Tumor Response 1 Cohort 1 SCC Right Axillary Pre-Injection: 2.5 × 1.5 (cm) Pre-Injection: 100% Primary Lymph Node Day 28: 2.5 × 1.6 (cm) Day 28: +6.6% unknown Day 56: N/A (Resected) Day 56: N/A (Resected) 2 Cohort 1 Melanoma Left Axillary Node Pre-Injection: 4 × 2.8 (cm) Pre-Injection: 100% Day 28: 3.8 × 2.5 (cm) Day 28: −15.2% Day 56: 4 × 2.5 (cm) Day 56: −10.8% 3 Cohort 1 Melanoma Right Breast Pre-Injection: 4.2 × 3.3 (cm) Pre-Injection: 100% Day 28: 3.6 × 2.8 (cm) Day 28: −27.3% Day 56: N/A (Next Trial) Day 56: N/A (Next Trial) 4 Cohort 2 Salivary Left Head & Neck Pre-Injection: 4.5 × 3.2 (cm) Pre-Injection: 100% Grand Day 28: 4.3 × 3.2 (cm) Day 28: −4.5% Day 56: 4.5 × 3.1 (cm) Day 56: −3.2% 5 Cohort 2 SCCHN Right Head & Pre-Injection: 2.5 × 1.7 (cm) Pre-Injection: 100% Neck Day 28: 2.2 × 1.7 (cm) Day 28: −12% Day 56: 2.6 × 1.7 (cm) Day 56: +4% 6 Cohort 2 Leiomyo Right Abdomen Pre-Injection: 2.5 × 2.0 (cm) Pre-Injection: 100% sarcoma Day 28: 2.2 × 2.0 (cm) Day 28: −12% Day 56: N/A (Next Trial) Day 56: N/A (Next Trial) 7 Cohort 3 Lung Right Pelvis Pre-Injection: 1.7 × 1.5 (cm) Pre-Injection: 100% Cancer Day 28: 1.7 × 1.4 (cm) Day 28: −6.7% Day 56: 1.7 × 1.4 (cm) Day 56: −6.7% 8 Cohort 3 Melanoma Left Pre-Injection: 3.3 × 1.4 (cm) Pre-Injection: 100% Musculoskeletal Day 28: 2.8 × 1.1 (cm) Day 28: −33.4% Soft Tissue Day 56: 2.5 × 0.8 (cm) Day 56: −56.8% 9 Cohort 3 NSCLC Right Axillary Node Pre-Injection: 3.5 × 4.7 (cm) Pre-Injection: 100% Day 28: 4.8 × 3.5 (cm) Day 28: +2% Day 56: 5.0 × 3.7 (cm) Day 56: +12.4% 10 Cohort 3 SCCHN Right Head & Neck Pre-Injection: 2.8 × 1.8 (cm) Pre-Injection: 100% Day 28: N/A (Not evaluable) Day 28: N/A Day 56: 3.1 × 2.1 (cm) Day 56: +29% 11 Cohort 3 SCCHN Right Head & Neck Pre-Injection: 5.0 × 2.6 (cm) Pre-Injection: 100% Day 28: 7.2 × 3.2 (cm) Day 28: +77.2% Day 56: N/A (PD) Day 56: N/A (PD) 12 Cohort 3 Melanoma Left Lower Leg Pre-Injection: 1.5 × 1.5 (cm) Pre-Injection: 100% Day 28: N/A (Not evaluable) Day 28: N/A (Not evaluable) Day 56: N/A (PD)-new lesion) Day 56: N/A (PD-new lesion) 13 Cohort 3 Sarcoma Left Head & Neck Pre-Injection: 5.5 × 3.4 (cm) Pre-Injection: 100% Day 28: N/A (Withdraw) Day 28: N/A (Withdraw) Day 56: N/A (Withdraw) Day 56: N/A (Withdraw) 14 Cohort 3 Basal Cell Right Head & Neck Pre-Injection: 2.8 × 1 (cm) Pre-Injection: 100% Cancer Day 28: 1.7 × 0.9 (cm) Day 28: −45.4% Day 56: N/A (Next Trial) Day 56: N/A (Next Trial) 15 Cohort 3 Gall Left Liver Pre-Injection: 3.5 × 2.9 (cm) Pre-Injection: 100% Bladder Day 28: 2.9 × 2.8 (cm) Day 28: −20% Cancer Day 56: 4.3 × 4.4 (cm) Day 56: +86% 16 Cohort 3 Breast Left Liver Pre-Injection: 1.5 × 0.9 (cm) Pre-Injection: 100% Cancer Day 28: N/A (Withdraw) Day 28: N/A Day 56: N/A (Withdraw) Day 56: N/A SCC = Squamous Cell Cartinoma SCCHN = Squamous Cell Cartinoma Head & Neck NSCLC = Non Small Cell Lung Cancer

As shown in the above tables, no dose-limiting toxicity, or maximally tolerated dose was identified. The virus TRAD was well-tolerated at doses producing infection in the cancer cells, demonstrated early antitumoral activity as reflected in the reduced tumor sizes, and is an excellent cancer treatment candidate.

In the clinical trial, the virus TRAD according to the presently claimed virus, was successfully and safely administered to 16 patients, and no serious side effects were observed. These results illustrate the targeting specificity of TRAD (i.e., the minimal, or few side effects indicate little or no replication in normal cells), and show the virus TRAD replicates in and kills cancer cells.

The following data provide additional details of data obtained from three patients out of the above-described sixteen patients in the clinical trial.

Patient #01103 (No. 3 in Table 2)

Diagnosis: Metastatic Melanoma

In March of 2004, a 35 year old female, was diagnosed as advanced melanoma with metastasis to the liver and spleen. The patient was treated with temozolomide from May 2005-August 2005 with stable disease. She was also treated with interferon in July 2004 with stable disease. Recently, she was treated with an experimental dendritic cell vaccine, with overall response of PD. The baseline expression of hTERT mRNA in the biopsy tissue to be injected was positive.

On Feb. 15, 2007, the patient received a single intratumoral injection of TRAD (1×10¹⁰ VP) into the right breast mass (4.2×3.3 cm [13.9 cm²]).

On the next day after treatment, she experienced mild soreness at injection site, which was considered related to TRAD injection. And as the evidence of inflammation at the injected tumor, the peak of serum IFN-gamma and the peak of body temperature (37.1° C.) were observed on day 1 after the injection.

On 28 days after injection, 27.3% tumor shrinkage was observed at treated tumor lesion (3.6×2.8 cm [10.1 cm²]).

After the evaluation at the visit on day 28, the patient was subsequently enrolled into another clinical trial.

Patient #01208 (No. 8 in Table 2)

Diagnosis: Metastatic Melanoma

On February of 2007, a 72 year old female with history of COPD, was diagnosed as melanoma at the left ankle. She received a knee amputation on Apr. 5 of 2007 and a biopsy of the left inguinal node on the same day to find recurrence in the inguinal node. The recurred tumor was found at a left medial thigh node on May 11, 2007. She received 2 doses of interferon from Jun. 11 to 18 of 2007. The baseline expression of hTERT mRNA in the biopsy tissue to be injected was positive.

On Jul. 30 of 2007, the patient received a single intratumoral injection of TRAD (1×10¹² VP) into the tumor at medial left thigh (3.3×1.4 cm [4.6 cm²]) of melanoma. She experienced mild bruising at the injection site and mild skin lesion from removing band-aid on day 7. As the evidence of inflammation at the injected tumor, the peak of IL-6 and IL-10 peak were observed on Day 1. On the day 22, mild panic attack prior to visit. The panic attach was thought to be due to information the patient heard about her brother. The patient contacted her physician's office and was instructed to take Xanax for her anxiety. The only adverse event thought to be probably related to study treatment was bruising at the injection site.

On day 28 after injection, 33.4% tumor shrinkage was observed at treated tumor lesion (2.8×1.1 cm [3.1 cm²]), and pathological response were also observed at injected lesion. On day 56 after injection, 56.8% tumor shrinkage was observed at treated tumor lesion (2.5×0.8 cm [2.0 cm²]) (FIG. 10).

In addition, as shown in the FIG. 10, on Day 0, a large part of the tissue was basophilic (“x10 obj” of upper panel) and melanoma cells and lymphocytes infiltrated (“x40 obj” of upper panel), in contrast, on Day 28, tissues were rather eosinophilic (“x10 obj” of lower panel) and plasma cells infiltrated and there were no apparent tumor cells (“x40 obj” of lower panel).

Patient #01214 (No. 14 in Table 2)

Diagnosis: Basal Cell Carcinoma

In 2001, a 54 year old male, was diagnosed as basal cell carcinoma in back. He had it removed surgically, and was diagnosed with basal cell cancer. One year later his disease recurred at the scar on his scalp. He then received a second surgery. Lung metastasis was found and followed by 2 cycles of Cisplatin and 5-FU in February 2005. The recurrence at scalp was found on November 2007, and at the right neck and bilateral supraclavicular region, metastasis was found on Dec. 6 of 2007. The baseline expression of hTERT mRNA in the biopsy tissue to be injected was positive.

On Jan. 17 of 2008, he received a single intratumoral injection of TRAD (1×10¹² VP) into the tumor at right suboccipital scalp (2.8×1.0 cm [2.8 cm²]). He experienced mild fever, achiness and chills on the day of study treatment. These adverse events were thought to be probably related to TRAD injection.

On day 28 after injection, 6.7% tumor shrinkage was observed at treated tumor lesion (1.7×0.9 cm [1.5 cm²]). On day 56 after injection, the tumor size of treated tumor lesion remained the size as on 28 days after injection.

In the clinical trial, the virus TRAD was successfully and safely administered to the patients, and no serious side effects were observed. In general, it is highly important for the human patient in the cancer treatment that no serious side effects were observed. Therefore, the above-described results (i.e., causing tumor shrinkage without serious side effect in human patient) show surprising and advantageous effects of the present invention which is unpredictable for the one of ordinary skill in the art.

All publications, including but not limited to, issued patents, patent applications, and journal articles, cited in this application are each herein incorporated by reference in their entirety.

Although the invention has been described above with reference to the disclosed embodiments, those skilled in the art will readily appreciate that the specific experiments detailed are only illustrative of the invention. It should be understood that various modifications can be made without departing from the spirit of the invention. Accordingly, the invention is limited only by the following claims. 

1. A polynucleotide cassette comprising an hTERT promoter operably linked with an E1A gene, an IRES sequence and an E1B gene, in that order, wherein the polynucleotide cassette comprises a nucleotide sequence having at least 99% identity to the nucleotide sequence consisting of SEQ ID NO:12, wherein said polynucleotide cassette enables an adenovirus to replicate selectively in tumor cells.
 2. A recombinant adenovirus comprising the polynucleotide cassette of claim
 1. 3. A polynucleotide cassette comprising an hTERT promoter operably linked with an E1A gene, an IRES sequence and an E1B gene, in that order, wherein the polynucleotide cassette comprises the nucleotide sequence of SEQ ID NO:12.
 4. A recombinant adenovirus comprising the polynucleotide cassette of claim
 3. 5. A recombinant adenovirus comprising the nucleotide sequence of SEQ ID NO:14. 